While Portland is fortunate to have an abundant supply of drinking water, once the hot days settle into the Willamette Valley, people begin to ask whether we have enough water to get us through the summer.
The answer is yes.
How We Plan for Summer Water Supply
Each year, our summer supply planning experts develop a Seasonal Water Supply Augmentation and Contingency Plan also known as the Seasonal Supply Plan. This plan evaluates the amount of water that is available from the Bull Run reservoirs and groundwater sources, projected weather forecasts, water releases that we make to improve fish habitat, and the amount of water the region typically uses. Between careful management and the region’s strong conservation efforts, we are prepared to meet Portlanders’ summer water supply needs.
Water supply by month for 2015 and 2018, which are two recent years with hot, dry summers, the historical average daily storage, and 2019 to date.
Did you know that the Bull Run reservoirs can fill up quickly after a long summer drawdown? A significant fall rain event can abruptly refill Bull Run Reservoirs in as little as two to three days. That’s about 150 million gallons each hour filling up the reservoirs.
How Your Water System Works
The Bull Run water system is designed to capture and store rainfall from the rainy season to provide enough water during the dry summer months.
Along with stream inflows into the Watershed and the billions of gallons stored in the two reservoirs, there is enough supply to meet water demand during most years just from the Bull Run Watershed.
During drier years, the Columbia South Shore Well Field groundwater source is one of the options we can draw upon to make up any supply deficits.
As we do every year, we are carefully watching our water supply throughout the summer.
Drawdown occurs when water demands for Portland’s drinking water, plus fish streamflow needs, are higher than what the streams carry into the reservoirs. This happens every year until the fall rains return and refill the reservoirs. This year, drawdown began on May 7.
Two Sources, More Choices
Did you know that the Bull Run Watershed gets its water primarily from rain, not snow?
The watershed gets approximately 135 inches of rain each year, about three to four times more rain than we get here in town.
Portland’s secondary water supply is the Columbia South Shore Well Field. The well field has 25 wells in three aquifers that can produce up to 80 million gallons per day. Each year during drawdown, our Operations folks perform a groundwater maintenance operation to ensure that the well field is operational in the event it is needed for emergency supply.
With an average daily summer water demand of 120 million gallons, the bureau carefully plans to meet the needs of our customers.
Conserving Water Starts at Home
The Water Bureau’s best partner in ensuring that we have more than enough water for years to come is you!
The bureau has a Water Efficiency Program where you can learn more about using water wisely all year round with information about native plants in your garden and high-efficiency devices for your showers, faucet and toilets.
Water Planning Information
For updates and more information about how we plan for future water use, visit portlandoregon.gov/water/seasonalsupply.